After dewinterizing this year I have a slow dribble from the shower even when it is turned off. I think maybe the cartridge needs to be replaced. I've gotten this far:

I think the next step is to remove the pin, but it's behind the shower wall. I see other references in this thread to this problem which suggest removing the whole thing, I can't figure out how to do that.

Also, as far as I can tell there's no way to access behind the wall with my layout.

Our shower wand dribbles all of a sudden and when hanging up is loud as water drips out. The sticker on the back of the wand states it is supposed to do that to let you know water line is on. It had not done that for years and all of a sudden it did this camping trip. I took out the washers(2) that were dried and old out of the wand and replaced with new 5/6 rubber washers. It helped the wand pressure but still dribbles. I started to do as you, looking at the pic but did not want to get into trouble tearing out things until I got better info. You tube shows some good plumbing repairs. So still gonna wait for advice before doing anything else.